System for monitoring the temperature of wheel bearings in railroad cars

ABSTRACT

A system is described for automatic detection of overheated wheel bearings of railroad cars and carriages. Signals representing the temperature of such bearings are generated by temperature sensors that are installed in close proximity of the wheel bearings. The signals are amplified, digitized and, to prevent false indications, averaged for each individual bearing. The averaged signals from each bearing are than compared to the averaged signals from the other three bearings of the same car or vehicle. If the signal from any bearing deviates by a present magnitude value, an alarm signal is generated and transmitted to a central monitoring location. The signals from each bearing are uniquely identified by a code. Light emitting diodes are installed close to the bearings and light up to indicate overheating. The electric power for the system is generated by an electromagnetic generator, which responds to the vibrations of the moving car.

This application claims priority to my provisional application60/550,432 filed Mar. 8, 2004, which by this reference is incorporatedherein.

FIELD OF INVENTION

The instant invention relates generally to systems for detecting defectsin wheel bearings of railroad car due to overheating by monitoring thetemperature of such bearings.

BACKGROUND OF THE INVENTION

Overheating of wheel bearings in railroad cars can lead to seriousaccidents if not noticed before major damage occurs. The Office ofSafety Analysis of the Federal Railroad Administration reports thatduring the period between January and November 2003 there have been1,477 train accidents attributable to equipment defects and failures. Infact, 180 of such incidents were directly related to bearing or breaksfailures (See “Federal Railroad Administration, 2003 Report on TrainAccidents due to Equipment Failures”). Such accidents are especiallydangerous when they involve passenger carriages and freight carscarrying hazardous cargo, such as explosives and nuclear waste.

A system for detection of overheating in wheel bearings, aside of itsvalue as a means for preventing accidents, injuries and deaths, wouldalso allow for rail cars' maintenance schedule to be implemented in atimely fashion—an opportunity for cost-saving.

Federal Railroad Administration's “Rolling Stock program” placesemphasis on the development and improvement of equipment defectdetection via wayside and onboard systems. Such systems promote earlydefect detection and help prevent derailments due to equipment failure.They also permit condition-based maintenance of car and locomotivecomponents.”(See “Federal Railroad Administration, Railroad Research andDevelopment Program, Section 4.3 Rolling Stock and Components”)

The advent of inexpensive and reliable sensors, microprocessors andelectronics makes such automated systems for detection of overheatingpractical and cost-effective.

SUMMARY OF THE INVENTION

It is a feature of he present invention to provide an on-board systemfor railroad cars and carriages, which detects and provides signals thatalert responsible personnel to incidents of bearing overheating andidentify the location of the overheated bearings.

The system provided by the invention improves heretofore-proposedsystems such as disclosed in U.S. Pat. Nos. 3,629,572; 3,697,744;3,731,087; 3,812,343; and 4,659,043, which include the wayside systemsrelying on detection of infrared signatures from overheated bearings.The present invention provides an on-board system, which is continuouslyoperating thereby enabling real time detection of bearing failures dueto lack of lubrication or mechanical defects as evidenced byoverheating. The wayside IR detectors also frequently suffer from poorsensitivity; are widely spaced so that they may not detect an overheatedbearing in time to prevent an accident; are not responsive to scanningbearings of cars wherein several (say, three) different sizes of wheelsare employed; are prone to falsely respond to sources of IR radiationother than the car bearings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system for detection of overheating inwheel bearings of railroad cars in accordance with the invention.

FIG. 2 is a block diagram of another embodiment of the system fordetection of overheating in wheel bearings of railroad cars inaccordance with the invention.

FIG. 3 is a block diagram of a central monitoring station for the systemdepicted in FIG. 2.

DETAILED DESCRIPTION

With reference to FIG. 1, temperature sensors 10, 11, 12, and 13 areinstalled in close proximity to the bearings of each of the wheels of arailroad car or carriage. Railroad cars usually have four axles andeight wheels, however, only the sensors for four wheels are shown; thesensors for all eight wheels are identical. The sensors generateelectrical signals analog to the temperature of these bearings. Thesignals are amplified by the amplifiers 14, 15, 16, and 17 and passed onto a multiplexer module 26, which contains a solid state switchingcircuit that continuously cycles, serially selecting inputs fromamplifiers 14, 15, 16, and 17 and directing the signals from theseinputs to the output 28. The cycling is controlled by the clock signalsfrom the module 30 via line 27.

Module 30 is an A/D converter that converts the signals analog to thebearing temperature into digital data. Module 30 also contains a digitalclock and a circuit for imparting a string of code that identifies thebearing where the information originates. The digital data compriseinformation on the temperature of the bearings and the bearing I.D.code. The data from module 30 (consisting of four groups of temperaturereadings and accompanying codes) are fed into the comparator module 33.This module contains a microprocessor or logic programmed to temporarilystore several consecutive temperature readings from each bearing andcompute the average temperature values of these readings. The module 33continuously compares the magnitudes of the averaged temperature datafrom the four sensors 10, 11, 12, and 13 with the temperature data fromeach sensor for each cycle of four groups of temperature data andgenerates an overheating alarm signal if and when it determines that thetemperature data from one of the bearings indicates that the temperatureexceeds by a preset limit value the average temperature from all four orjust the other three bearings. As a result, false alarms are preventedthat could be generated in hot weather conditions raising thetemperature in all wheel bearings; the effects of any spurious signalsare also suppressed. Module 33 also attaches the I.D. code generated inthe module 30 corresponding to the overheated bearing to any alarmsignal, thus identifying the specific bearing, which is overheating.

The alarm signal is input into module 36, which acts as a demultiplexerand causes one of the outputs 37, 38, 39, or 40 corresponding to anoverheated bearing to activate one of the LEDs 22,23, 24, or 25. TheLEDs are mounted at a convenient location near the carriage or vehiclewheels and are intended to facilitate visual determination of adefective bearing, i.e., which of the bearings had overheated. Othertypes of signaling devices could also be used instead of LEDs.

The data from the module 36 are also entered into the transmittingmodule 42, which transmits via the antenna 44 the alarm signal to acentral monitoring station in the locomotive. Alternately the alarmsignals can be transmitted via a wire link to the central monitoringstation from the terminal 43.

The system is self-powered to simplify the installation. The magnet core50 of the solenoid coil 49 in the power generator is suspended onsprings 51 and 52 and moves vertically up and down as the carriage orthe vehicle moves. As a result, electric current is generated in thecoil of the solenoid 49. The current is rectified by the diode 48, usedto charge the battery 46 and to pass through the resistor 47 to thezener diode 45, which maintains the voltage at the desired level of,say, five volts. The terminal 53 is connected to terminals 18, 19, 20,21, 29, 31, 34, 41, and 54 to provide power to the system. Alternately,the system could be powered from the power bus of the railroad car orcarriage or other vehicle.

The temperature sensors may be thermocouples, thermistors, fiber optictemperature sensors, and other types, though thermistors and fiber opticsensors have two advantages over thermocouples in this application inthat they do not require a reference (cold) junction and are generallymore rugged.

FIG. 2 depicts another embodiment of the system. Separate but identicalmodules A, B, C, and D are installed in the proximity of the railroadcar or carriage bearings. The railroad cars have four axles and eightwheels, however, only the sensor modules for four wheels are shown; thesensor modules for all eight wheels are identical. Each module isself-contained and self-powered, thus there are no wired connectionsbetween the modules, which in some cases may facilitate the installationof the monitoring system.

Each module comprises temperature sensors 50, 60, 70, and 80, installedin close proximity of the wheel bearings. The analog signals from thesesensors are amplified in 51, 61, 71, and 72; then the amplified signalsare passed to the A/D converters 52, 62, 72, and 82. The digitizedsignals are input, respectively, into modules 53, 63, 73, and 83 where adigital code identifying each particular bearing is generated andattached to the signal string. Next, the signals are fed intotransceivers 54, 64, 74, and 84, which transmit the data to the centralmonitoring station depicted in FIG. 3. Modules 54, 64, 74, and 84 alsoreceive signals from the central monitoring station when an overheatedbearing is detected. When such a signal is received, modules 54 through84 activate the respective LEDs 50A, 60A, 70A, and 80A that are situatedclose to the wheel bearings to provide visual indication of a fault.

Each module is equipped with a power generator 55-58, 65-68, 75-88, and85-88, as described with reference to FIG. 1 that provides the electricpower to the components of each module A, B, C, and D. If a car or acarriage has more than four wheels, the appropriate number of moduleswould be installed.

Referring now to FIG. 3, which shows in a block diagram format thecentral monitoring station, module 90 is a transceiver which receivedsignals from the remote modules A, B, C, and D of FIG. 2, and transmitssignals back to these modules when an overheated bearing is detected,thus activating the appropriate LED. The signals from all remote modulesare input via terminal 92 into the control module 94, which temporarilystores and averages the digital signals received from each module andcompares these averaged values to each other. If the magnitude of one ofthe values exceeds a preset level, an alarm is initiated. The alarm isvisually displayed on the display module 95 and alarm sound isgenerated. In addition, the control module 94 sends a signal back totransceiver module 90, which transmits a signal to one of the modules,A, B, C, or D to activate the corresponding LED. Power to the centralmonitoring station is supplied via terminals 96.

1. A system for detection of overheating in wheel bearings of vehicleshaving a plurality of bearings comprising temperature sensors situatedin close proximity of said plurality of wheel bearings, said temperaturesensors responding to the temperature in said bearings and generatingelectrical signals representative of said temperature, means forprocessing said signals, and for generating alarm signals identifyingoverheated one or more of said bearings when the temperature of one ormore of said plurality of bearings as compared to the averagedtemperature representing signals from other of said plurality bearingsof the same vehicle exceeds a preset value, and means responsive to saidalarm signals for identifying the location of the bearings responsiblefor said signals exceeding preset value.
 2. A system according to claim1 in which said means for processing signals comprise: means foramplifying said temperature-representing signals, means for temporarilystoring a plurality of said temperature representing signals from eachsaid bearing and computing the average value of the magnitudes of saidstored temperature representing signals means for comparing said averagevalue of said temperature representing signals with value of temperaturerepresenting signals originating in said temperature sensors signalsfrom all other wheel bearings, generating an alarm signal when thedifference between said values of said temperature representing signalsfrom any said sensors in proximity to said one or more of said bearingsexceeds by a preset value said average value, means for generating aunique code identifying the specific location of said overheatedbearing, and means for utilizing said code with said alarm signal toidentify overheating in one or more of said plurality of bearings.
 3. Asystem according to claim 1 in which a central monitoring stationreceives the information from said identifying means and generates adisplay of the fault location and also generates a visual and audiosignal to alert the responsible personnel to the fact that a fault inone or more of said wheel bearings has been detected.
 4. A systemaccording to claim 1 in which said temperature sensors are selected fromthe group consisting of thermocouples, thermistors, fiber optictemperature sensors, resistance temperature sensors, and diodetemperature sensors.
 5. A system according to claim 1, furthercomprising means for transmitting said signals as alarm indicating data.6. A system according to claim 5 wherein means responsive to said datafacilitates visual indication of a said overheated bearing is installedin close proximity of said bearings.
 7. In a system according to claim 6wherein said means, which facilitate visual indication are lightemitting diodes included in proximity of each of said bearings.
 8. Asystem according to claim 1 further comprising means for providing theelectric power for energizing said system including electromagneticgenerator electromagnetic generator in which a magnetic core isvertically suspended by springs within a solenoidal coil, said coremoves up and down in response to the vibrations incurred by said cars asthey travel over the rails, said coil in response generating electriccurrent, or piezoelectric means used to generate electric current topower said system components.
 9. A system for detection of overheatingin wheel bearings in a railroad car or other vehicle having a pluralityof wheel bearings comprising individual temperature-sensing modulessituated in close proximity of each of said wheel bearings, saidtemperature-sensing modules responding to the temperatures of saidbearings and generating electrical signals representative of saidtemperatures, called temperature responsive signals hereinafter TRS,means for processing said TRS and for generating alarm signals when theTRS for one or more of said plurality of bearings exceeds a preset valueas compared to the TRS from the other of said plurality of bearingsthereby providing data identifying overheating one of said plurality ofbearings and their location and for display or transmission.
 10. Asystem according to claim 9 in which said means for processing saidsignals comprise means for amplifying said signals. means for digitizingsaid signals means for generating codes identifying a particular moduleand attaching said code to said digitized signals thus producing acomposite digital signal means for transmitting said composite signal toa central monitoring station and activating said display comprisinglight-emitting diodes situated near each of said temperature-sensingmodules.
 11. A system according to claim 9 in which each saidtemperature-sensing module includes a electromagnetic generator or apiezoelectric generator which provides power to said modules.
 12. Asystem according to claim 10 in which said central monitoring stationcomprises means for receiving and transmitting signals from and to saidtemperature-sensing modules, means for processing said signals, andmeans for displaying said alarm signals.
 13. A system according to claim9 in which said means for processing said signals temporarily storessaid signals from each said temperature-sensing modules, computesaverages of said stored signals, compares the magnitudes of saidaveraged signals to each other, and generates said alarm signal if oneof said averaged signals exceeds the other averaged signals by a presetvalue of their magnitude.